[wlachan]

I repaired this lens once and the aperture mechanism is a little more complex than some other Pentax primes. Also, I discovered the opening for the silver aperture shaft is too close to the greasy helical. So, to fix the problem properly, you don't just flush the blades clean, any leaked grease along the path has to be cleaned as well. I have found lacquer thinner is excellent for this purpose.

[kp0c]

Alright, a quick update for all those who helped me and for those who he might help : I put some lighter fluid on the aperture blades mechanism using a cotton tip (I would let the cotton tip gets full of lighter fluid, and then, gently rubbing the proper are within the lens with it.)
The result so far are very, very good. The aperture seem snappy as new. I will need to reassemble it before I know for sure, but I would say we have come a long way already!

I will let you know when I have tested the lens more thoroughly.

So again, thank you soo much for all your comment and help, I love our little community!

Karl

[kp0c]

Rereading my previous post, I would say I was a little too optimistic haha! (That is so very me... still, I better be over happy than always sad right?). Anyway. The aperture are still acting up. I will let it dry t'ill the morning and give it another cleaning session... we'll see how it goes tomorrow night. However, my feeling is that the problem is elsewhere... I'm starting to develop a theory. We'll find out soon enough, or at least, I hope so.

[MysteryOnion]

I've had four lenses with similar issues, the grease from the focus threads (helicoid) starts to separate due to excessive heat (maybe sitting in a car parked in the sun for a long time). The oil that seperates will slowly run down into the cup portion of the aperture assembly. This first stage problem is harder to spot and intime it will finally climb inside the gap that the blade are located in. Lighter fluid will loosen things up for a little while, but can also help to carry the running oil deeper into the aperture assembly. In range finders the use of lighter fluid is very helpful, however, not always so in lenses that rely on fast auto-apertures. In all four lenses I've had to fix, I had to pull fully apart... from front and then rear and then disassemble the aperture assembly.

[gp1806]

Rereading my previous post, I would say I was a little too optimistic haha! (That is so very me... still, I better be over happy than always sad right?). Anyway. The aperture are still acting up. I will let it dry t'ill the morning and give it another cleaning session... we'll see how it goes tomorrow night. However, my feeling is that the problem is elsewhere... I'm starting to develop a theory. We'll find out soon enough, or at least, I hope so.

You might have to remove all the glass elements and flush the aperture with lighter fluid. I did that once, I used cotton balls placed underneath the aperture blades (don't push too hard) and squirted lighter fluid on the top side. That flushed the oil out of the aperture mechanism and onto the cotton balls. I used many cotton balls to do that. Don't let the lighter fluid run all over the inside of the lens. Change the cotton balls when they get wet. I kept repeating this until the cotton balls did not show any signs of oil. Open a window to get fresh air, a small fan might be good. This procedure worked for me.

[mickeyobe]

GP1806 did it the right way.
A little patience is required but it does work.
It is well worth the time and the effort.

Mickey

[TomB_tx]

Too much flushing on the partly assembled lens can also flush remaining lube from the helicals, making the inner barrel loose in the threads. I agree with MysteryOnion - best is to disassemble (carefully and taking pictures/notes of how it all fits), clean each part, then reassemble. I would also remove the helical mechanism, clean and re-lube it. After going so far into a lens, why not do a full CLA?

[kp0c]

A quick update.

I did manage to properly clean the lens using a combination of methods from you guys. Thank you again, my m-35mm is now back in shape, with a very snappy aperture!!

Thank you everyone for your help.